Green’s Dictionary of Slang

(US) hunchbacked.

1873		J. Greenwood In Strange Company 7: She wasn’t very big because of her humpty back.
1881		Dundee Courier (Scot.) 8 Mar. 7/4: He was evidently deformed [...] his back being slightly ‘humpy’.
1890		‘’Arry on Equality’ in Punch 22 Feb. 85/2: He’s got a white face, and is humpy, and lives in a sort of a hutch.
1896		A. Morrison Child of the Jago 16: Nor yut the boy — ’umpty-backed ’un?
1898		E. Pugh Tony Drum 27: Wasn’t you humpy neither?
1944		C.S. Montanye ‘Shoulder Straps’ in Thrilling Detective Feb. 🌐 Humpty Keller, as his name implied, was a hunchback.
1946		Mezzrow & Wolfe Really the Blues 33: Faded and torn and built for a humpy giant to begin with.